Containerized applications have introduced a new paradigm in software development that provides extensive scalability, availability, portability, and cost savings across the application lifecycle. However, migrating to a containerized application architecture from a traditional software application would be a daunting task. This complexity further increases when trying to move to a complete container orchestration platform like Kubernetes. In this post, let’s discuss the major pain points when migrating to a containerized environment and how to tackle them effectively to create a smooth migration plan.
Four Major Considerations When Designing a Kubernetes Migration Plan
We need to tackle multiple aspects before migrating to Kubernetes depending on the application architecture, dependencies, databases, and compliance requirements. In this section, we will explore the common considerations for the Kubernetes migration process.
1. Choosing a Kubernetes Platform
The first thing to consider is the Kubernetes platform itself. Kubernetes will be the orchestration engine, yet the primary concern will be how the underlying infrastructure is provisioned and managed there.
Users can create Kubernetes clusters on any environment from on-premise to a cloud platform. However, the platform you choose will decide who is going to handle the responsibility of infrastructure management. If your target is to move to an on-premise Kubernetes environment, the organization will have to hold the complete responsibility of provisioning and maintaining the infrastructure, networking, and Kubernetes cluster.
On the other hand, if your goal is to move to a cloud-based solution, you can choose one of the following options.
- Provision cloud servers, yet install and configure the Kubernetes cluster yourself. This option provides users with utmost scalability with all the benefits of cloud computing. However still, the organization will have to bear the responsibility of cluster configuration and management.
- Use a managed Kubernetes solution. This option will pass all the responsibility of infrastructure provisioning and management to the cloud provider. Therefore, users can simply create and configure the Kubernetes cluster without worrying about the underlying infrastructure. This approach enables users to get up and running with the application quickly while reducing CapEx and OpEx. Services like Amazon Elastic Kubernetes Service and Azure Kubernetes Service (AKS) are some of the available managed Kubernetes solutions. Users can extend them further by opting for a fully serverless solution like AWS Fargate.
- Use a hybrid deployment. This option allows users to divide the workloads between on-premise and cloud environments. Hybrid deployments are useful when dealing with highly sensitive data as they can be kept on premises while only exposing the necessary data to the wider internet. Services like Amazon EKS natively support hybrid deployments and can be extended further using Amazon EKS Anywhere and Amazon Outpost to run AWS infrastructure in an on-premise datacenter.
2. Data Migration Strategy
Next comes the data migration part of the migration strategy. Whether the data is structured or unstructured, stored in a database or a data volume, we need to consider how to store, access, and migrate these application data into Kubernetes.
Database migrations are relatively easy regardless of the database type, and the only considerations arise with data schemas and the required feature set of the cloud database. Yet, most workloads can be successfully migrated to managed cloud database solutions, and for edge cases, there is always the option to run the database on a provisioned instance. For unstructured data, users can utilize cloud storage solutions like Amazon S3, Azure Blobs storage, and long-term archival storage like AWS Glacier.
One major consideration here is data migration which can be a costly and time-consuming process depending on the data structure and size. Another factor to consider when it comes to data migration is the compliance requirements, as it will be the most vulnerable point for the application data.
With all the above factors, users need to ensure that a proper back strategy is in place to securely back up Kubernetes configuration, application, and user data.
3. Network Infrastructure
When deploying an application into a Kubernetes cluster, users must think of networking both internally within the cluster as well as externally. We need to properly structure the internal network connectivity between each container depending on the application architecture, workload, and communication methods. Then think about how and which endpoints should be exposed to end-users.
Kubernetes offers some tools like Kubernetes Ingress, load balancers, services, and network policies to create a robust network for the application. Even with a properly configured cluster, we will have to rely on external services like firewalls, external load balancers, and monitoring tools to gain more granular control over the network access to the cluster.
4. Deployment Strategy
It is vital to consider how to deploy future releases to the Kubernetes environment rather than simply migrating the existing application. This might lead to a complete overhaul of the current deployment strategy, and the most viable solutions will include automated CI/CD pipelines. The Kubernetes cluster should be an integrated component in the delivery pipeline when following a DevOps approach.
As a whole, organizations should decide on a deployment strategy that supports direct deployments to Kubernetes before migrating. Otherwise, users will face complexities when trying to deploy new application versions resulting in delays and bugs for end users.
Planning the Migration
Even after considering all the points mentioned above, application migrations can still be a daunting process. It is also essential to ensure that the end-users are not affected during the migration process.
The planning and migration process should be a collaborative effort, including all the departments within an organization. This way, we can ensure that all aspects of the application are included in the migration plan. You can even break the migration into multiple stages, with each stage considered a separate migration process. This approach will allow users to reduce the scope to a more manageable level and minimize human errors as users can focus on one particular aspect.
This stage-based migration allows users to migrate and then test each aspect of the application separately. For example, we can test if the data has been successfully migrated in the database migration stage before moving the application and mitigating any production issues. After completing all the stages, we can then move on to a testing phase to ensure the application functionality in the Kubernetes cluster. Finally, we can gradually provide end-users access to the application in the Kubernetes environment.
A proper disaster recovery plan should also be included in the migration plan to deal with any issues during and after the migration. It enables users to deal with any issues that might hinder the migration process while ensuring the continued availability of the application to end-users with limited disruptions.
The older application should not be decommissioned immediately after the migration as it can be kept as a backup. The organization should start the decommissioning process only after ensuring the smooth operation of the application in the Kubernetes environment.
Migrating to Kubernetes is a complex and time-consuming process. Yet, it can be accomplished with careful planning, a highly knowledgeable team, and robust disaster recovery plans, which are the cornerstones of successful workload migration.